AN  INVESTIGATION 


OF  A 

MODIFIED  BUNSEN  ICE  CALORIMETER 

BY 

VERA  VIVIAN  BASSETT 


THESIS 

FOR  THE 

DEGREE  OF  BACHELOR  OF  ARTS 

IN 

PHYSICS 


COLLEGE  OF  LIBERAL  ARTS  AND  SCIENCES 
UNIVERSITY  OF  ILLINOIS 


1922 


UNIVERSITY  OF  ILLINOIS 


i92_2__ 

THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 

Vera  Vivinn  Rqgs gt.-f. 

ENTITLED Jny_e§t_iga;5A^_.Q£ 


IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 
DEGREE  OF  3aCJaAlcr__££__&r_tL3 


/? . 

Instructor  in  Charge 


Approv 


HEAD  OF  DEPARTMENT  OF 


rfc» 


Digitized  by  the  Internet  Archive 

in  2016 


https://archive.org/details/investigationofmOObass 


TABLE  0?  COIT TENTS 


I  Introduction. 

II  Calorimetry. 

General  Methods. 

a.  Black’s  Calorimeter. 

b.  Laplace  and  Lavoisier’s  Calorimeter. 

c . Buns en ’ s Ice  Ca 1 or ime ter. 

Ill  Present  Investigation. 

Method  of  filling  Calorimeter. 

Investiga tion  of  Methods  of  Breezing  Later. 
He  suit  Obtained. 

IV  Conclusion. 


INVESTIGATION  OF  A MODIFIED  BUKSEI1  ICE  C LORI hK TER. 


I Purpose.  The  purpose  of  the  investigation  was  to  test 
the  action  of  a modified  Bunsen  Ice  Calorimeter.  Theory  shows 
that  the  Bunsen  Calorimeter  is  most  promising  for  the  determination 
of  specific  heat,  hut  the  results  of  the  experiments  are  dis- 
appointing, because  it  appears  that  the  instrument  has  defects. 

It  was  thought  that  the  modified  calorimeter  might  overcome  one 
of -these  defects. 

II  Calorimetry.  Calorimetry  is  the  process  of  measur- 
ing the  heat  which  a body  emits  or  absorbs.  The  apparatus  used 

in  this  process  is  called  the  calorimeter.  Quantities  of  heat  may 
be  measured  indirectly  in  a variety  of  ways,  in  terms  of  differ- 
ent effects  of  heat  on  material  substances.  The  most  important 
of  these  effects  are  change  of  temperature,  transformation  of 
energy  and  change  of  state. 

The  rise  of  temperature  of  a body,  where  heat  is 
imparted  to  it,  is  found  to  be  in  general  nearly  proportional 
to  the  quantity  of  heat  added.  The  thermal  capacity  of  a body 
is  measured  by  the  quantity  of  heat  required  to  raise  its  temper- 
ature one  degree,  and  is  necessarily  proportional  to  the  mass  of 
the  body  for  bodies  of  the  same  substance  under  similar  conditions. 
The  specific  heat  of  a substance  is  sometimes  defined  as  the 
thermal  capacity  of  unit  mass.  The  methods  of  measurement,  found- 
ed on  rise  of  temperature,  may  be  classed  as  thermometrio  methods, 
since  they  depend  on  the  observations  of  change  of  temperature 


2. 

with  a thermometer.  The  most  familiar  of  these  are  the  method  of 
mixture  and  the  method  of  cooling. 

The  method  of  mixture  consists  in  imparting  the  quantity 
of  heat  to  he  measured  to  a known  mass  of  water,  or  some  other 
standard  substance,  contained  in  a vessel  or  calorimeter  of  known 
thermal  capacity,  and  in  observing  the  rise  of  temperature  pro- 
duced, from  which  data  the  quantity  of  heat  may  be  found.  This 
method  is  the  most  generally  convenient  and  most  readily  applic- 
able of  calorimetric  methods,  but  is  not  always  the  most  accurate, 
because  some  heat  is  generally  lost  in  transferring  the  heated 
body  to  the  calorimeter,  and  some  is  lost  when  the  calorimeter  is 
raised  above  the  temperature  of  its  enclosure,  and  before  trie 
final  temperature  is  reached. 

A common  example  of  the  method  of  cooling  is  the 
determination  of  the  specific  heat  of  a liquid  by  filling  a small 
calorimeter  with  the  liquid,  raising  it  to  a convenient  temper- 
ature, and  then  setting  it  to  cool  in  an  enclosure  at  a steady 
temperature,  and  obse rving  the  time  taken  to  fall  through  a given 
range  when  the  conditions  have  become  fairly  steady.  The  same 
calorimeter  is  afterwards  filled  with  a known  liquid,  such  as 
water,  and  the  time  of  cooling  is  observed  through  the  same  range 
of  temperature,  in  the  same  enclosure,  under  the  same  conditions. 
The  ratio  of  the  times  of  cooling  is  equal  to  the.  ratio  of  the 
thermal  capacities  of  the  calorimeter  and  its  contents  in  the  two 
cases.  The  advantage  of  the  method  is  that  there  is  no  trans- 
ference or  mixture;  the  defect  is  that  the  whole  measurement 


. 


't 1 i Sr  ■’  wW . - 


3. 


depends  on  the  assumption  that  the  rate  of  loss  of  heat  is  the  same: 
in  the  two  cases,  and  that  any  variation  in  the  conditions,  or 
uncertainty  in  the  rate  of  loss,  produces  its  full  effect  in  the 
result,  whereas  in  the  previous  case  it  would  only  affect  a small 

correction. 

The  second  general  method  of  calorimetry,  that  based  on 
the  transformation  of  some  other  kind  of  energy  into  the  form  of 
heat,  rests  on  the  general  principle  of  the  conservation  of  energy, 
and  on  the  experimental  fact  that  all  other  forms  of  energy  are 
readily  and  completely  convertible  into  the  form  of  heat,  The  two 
most  important  varieties  of  this  method  are  mechanical  and  elec- 
trical. This  however  will  not  be  discussed  further  since  it  is 
not  applicable  to  the  present  investigation. 

The  methods  depending  on  change  of  state  are  theoret- 
ically the  simplest,  since  they  do  not  necessarily  involve  any 
reference  to  thermometry,  and  the  corrections  for  external  loss 
of  heat  and  for  the  thermal  capacity  of  the  containing  vessels 
can  be  completely  eliminated.  They,  nevertheless,  present  peculiar 
difficulties  and  limitations,  which  render  their  practical  applic- 
ation more  troublesome  and  more  uncertain  than  is  usually  supposed. 
They  depend  on  the  experimental  fact  that  the  quantity  of  heat  re- 
quired to  produce  a given  change  of  state  is  always  the  same,  and 
that  there  need  be  no  change  of  temperature  during  the  process. 

The  difficulties  arise  in  connection  with  the  determination  of  the 
quantities  of  ice  melted  or  steam  condensed,  and  in  measuring  the 
latent  heat  of  fusion  or  vaporization  in  terms  of  other  units  for 


. 


' 


5. 


three  concentric  tin  vessels;  in  the  central  one  was  placed  the 
body,  M,  whose  specific  heat  was  sought,  while  the  other  two  were 
filled  with  pounded  ice.  The  ice  in  compartment  A was  melted  hy 
the  heated  body,  while  the  ice  in  compartment  B cut  off  the  heat- 
ing influence  of  the  surrounding  atmosphere,  The  two  stopcocks 
2 and  D gave  issue  to  the  water  which  arose  from  the  melting  of 
the  ice.  In  order  to  find  the  specific  heat  of  a body  hy  this 
apparatus,  its  weight  M is  first  determined;  it  is  then  raised  to 
a given  temperature,  t,  hy  keeping  it  for  sometime  in  an  oil  or 
water  hath,  or  in  a current  of  steam.  Having  been  quickly  brought 
into  the  central  compartment,  the  lids  are  replaced  and  covered 
with  ice  as  represented  in  the  figure.  The  water  which  flows  out 
hy  the  stopcock  D is  collected.  Its  weight  B,  is  manifestly  that 
of  the  melted  ice.  The  calculation  is  then  made  as  in  the  pre- 
ceding case. 

The  two  calorimeters  just  described  were  not  adapted 
for  work  of  great  precision,  on  account  of  the  impossibility  of 
accurately  estimating  the  quantity  of  water  left  adhering  to  the 
ice  in  each  case.  This  difficulty  was  overcome  by  the  invention 
of  Bunsen's  ice  calorimeter, 

c.  The  Bunsen  calorimeter  was  invented  in  1870  by 
Hobert  Wilhelm  von  Bunsen,  Professor  of  Chemistry  at  Heidelberg, 
The  construction  of  the  instrument  is  given  as  follows.  (See 
Figure  3 ) . 


Figure  5. 

A cylindrical  test  tube  A was  fused  into  a larger  cylind- 
rical glass  "bulb  B which  v/&s  furnished  with  a glass  stem  CD.  I his 
stem  v/as  filled  with  boiled  mercury  which  also  occupied  the  bulb 
to  the  level  B.  i'he  remainder  of  the  bulb  B was  filled  with  pure 
boiled  water.  A calibrated  narrow  glass  tube  S,  furnished  with  a 
millimetre  scale  was  fitted  into  a cork  with  fine  sealing  wax. 

Hercury  was  then  forced  into  the  tube  S and,  by  adjusting  the  cor':, 

could  be  placed  at  any  convenient  point. 

In  conducting  the  experiment  the  first  operation  was  to 
freeze  some  of  the  water  in  bulb  B.  i’wo  cylindrical  semi  tin 
plate  vessels  were  partly  filled  with  alcohol  and  connected  by 
tubes  to  the  test  tube,  fhese  vessels  were  then  put  in  a freez- 
ing mixture  and  by  means  of  suction  cold  alcohol  was  passed  to  and 
fro  and  the  bulb  B reduced  to  the  freezing  point.  It  was  necessary 

for  the  air  freed  water  in  Bf  to  be  reduced  far  below  the  normal 

freezing  point  before  solidification  set  in,  while  the  outside  of 
the  bulb  became  covered  with  a coating  of  ice,  due  to  atmosphere. 

At  last,  where  the  temperature  had  been  greatly  reduced,  the 
formation  of  ice  suddenly  began,  and  spread  in  a few  seconds  from 
the  bottom  of  a to  the  top  of  B,  Within  these  limits  the  bulb 
was  filled  with  thin  plates  and  needles  of  ice,  but  from  the 


7. 


bottom  of  A to  the  level  of  the  mercury  belov;,  the  water  v/as  not 
frozen.  By  continued  cooling  a shell  of  solid  ice  was  gradually 
formed  around  A from  6 to  10  mm.  in  thickness. 

On  account  of  the  low  temperature  of  the  alcohol,  the 
ice  shell  was  much  below  zero,  and  if  the  instrument  was  not 
packed  in  snow  at  zero,  a slow  progressive  freezing  took  place 
in  the  water  for  a long  time.  Bunsen  found  that  in  this  manner 
about  2 gras,  of  water  Were  frozen  at  the  temperature  of  melting 
snow  during  the  first  seven  hours  and  that  this  progressive 
freezing  was  sensible  for  one  hundred  and  fourteen  hours, 
this  time  the  whole  apparatus  had  come  to  zero  and  freezing 
ceased.  In  order  to  interpret  the  indications  of  the  instrument 
a known  mass  of  water  LI,  at  a definite  temperature  &,was  intro- 
duced into  the  tube  A.  In  falling  to  zoro,  this  gave  out  a 
quantity  of  heat  KQ-,  and  in  consequence  of  the  melting  of  ice, 
the  mercury  in  the  tube  S receded  through  II  divisions  of  scale. 
I’his  gave  the  relation  between  the  quantity  of  heat  supplied  in 
an  experiment  in  tube  A and  the  corresponding  recession  of  mercury 
along  the  scale  St  for  if  Q is  the  quantity  of  heat  corresponding 
to  each  division  we  have:- 

m = Q.LT 

In  determining  the  specific  heat  of  any  substance,  a 
fragment  was  heated  and  dropped  into  the  test  tube  which  w as 
partly  filled  with  pure  distilled  water.  I'his  warned  the  water 
at  the  bottom  of  the  tube  and  tended  to  melt  some  of  the  ice 
which  in  turn  caused  the  mercury  to  recede  through  IT’  divisions 


8. 


on  the  scale.  Hence  if  M 1 was  the  mass  of  the  body,  and  O1  its 
original  temperature,  the  specific  heat  of  the  substance  could  be 
given  by  the  equation 

S MU  *=» 

~ “ Lf*Wr 

Bunsen,  in  a report  to  the  Philosophical  Magazine  in 
March  1871,  stated  that  the  old  instruments  were  not  accurate 
because  of  the  loss  of  so  much  liquid  and  heat.  He  made  the 
following  calculations  for  specific  heat  from  his  experiments. 


Water 

1.0000 

Silver 

0.0559 

Zinc 

0.0935 

Antimony 

0.0495 

Cadmium 

0.0548 

Sulphur 

0.1712 

One  of  the  chief  difficulties  encountered  was  the 
irregular  movement  of  the  mercury  column  due  to  slight  differences 
in  temperature.  Professor  8,  V.  Boys  thought  that  he  had  greatly 
reduced  this  difficulty  by  the  fusion  of  another  cylindrical  glass 
tube  on  the  outside  of  the  other  two.  He  thought  that  by  having 
the  ice  inside  separated  from  the  ice  outside  by  an  air  space, the 
passage  of  heat  would  be  greatly  reduced.  H.  L.  Callendar,  in 
his  report  on  Calorimetry  in  the  Encyclopedia  Brittanica,  stated 
that  very  good  results  were  obtained  by  enclosing  the  calorimeter 
in  a vacuum  jacket  which  would  practically  eliminate  conduction 
and  convection.  Radiation  would  also  be  reduced  if  the  jacket 
were  silvered  inside.  If  the  vacuum  was  really  good,  he  said  that 


9 


the  external  ice  hath  could  he  eliminated  for  the  majority  of 

purposes . 

Ill  Present  Investigation,  The  accuracy  of  Bunsen 
calorimeter  depends  essentially  on  the  care  with  which  all  • o 
air  has  been  expelled  from  the  water  enclosed  by  the  bulb  B 

(Figure  3a \ . 


Mr.  Preston  in  his  book  on  "Heat"  gave  the  following  method  for 
filling  the  instrument.  The  bulb  is  at  first  about  half  filled 
with  water,  and  placed  mouth  downwards  over  a lamp,  so  that  the 
water  can  be  boiled,  and  the  air  expelled  through  the  tube  CD. 
During  this  process  the  mouth  of  the  tube  CD  dips  into  a vessel 
of  boiling  water.  Where  the  water  in  the  bulb  has  been  boiled 
away  to  about  1/3  of  its  original  bulk  the  lamp  is  removed,  and 
as  the  instrument  cools  the  air  free  water  is  siphoned  over  into 
it  through  the  tube  CD  from  the  vessel  into  which  it  dips,  The 
instrument  is  now  placed  upright  and  the  water  siphoned  out  of 
CD,  which  is  dried  by  an  air  current.  The  final  filling-in  of 
boiled  mercury  is  done  with  a capillary  glass  tube,  so  as  to 
avoid  the  remaining  of  any  air  bubbles  on  the  sides  of  the  tube. 

This  method  was  followed  at  first  but  later  changes 


10. 


were  made  which  makes  the  process  more  easily  and  quickly 
accomplished.  A small  quantity  of  distilled  water  was  put  into 
hull  Bf  which  was  heated  to  steam  temperature,  "by  the  aid  of  the 
Bunsen  Burner,  and  allowed  to  "boil  for  several  minutes.  Air  was 
expelled  through  the  mouth  of  tube  Cl)  which  had  previously  been 
put  into  a dish  of  boiled  distilled  water  as  described  above. 

The  flame  was  then  taken  away  and  as  the  vapor  cooled  and  con- 
densed a vacuum  formed  which  brought  water  over  into  the  bulb 
until  it  was  about  half  filled.  At  this  point  the  mercury  was 
introduced  in  the  tube  by  means  of  pouring, and.  the  instrument 
put  back  onto  a ring  stand,  with  the  mouth  of  CD  into  boiled 
distilled  water  as  before,  and  boiled  again,  This  time  a great 
deal  of  air  was  expelled,  both  from  the  water  and  the  mercury. 

It  was  assumed,  after  considerable  boiling  that  the  air  was 
entirely  expelled  after  which  the  bulb  was  allowed  to  fill  with 
water  as  before.  This  was  left  over  night  in  this  same  position. 

A small  bubble  remained  at  the  joint  of  tube  CD  which 
was  brought  to  the  surface  D as  the  calorimeter  was  turned  up- 
right. CD  was  then  filled  with  mercury  by  a process  of  pouring 
and  pushing  with  a small  iron  wire  . 

Bee  Photograph  on  page  10a. 


11 


Experimentation  was  first  started  with,  a calorimeter  of 
the  ordinary  type  made  of  pyrex  glass,  The  process  of  freezing 
was  much  the  same'  as  described  previously,  except  in  the  matter 
of  the  freezing  mixture,  i’he  calorimeter  was  packed  in  shaved 
ice  and  several  methods  of  freezing  were  tried, 
attempt,  a small  quantity  of  ether  was  put  into  the  test  tube. 

Two  tubes,  which  had  been  forced  through  a cork,  were  put  down 


telpt  mi  or 


The  end  of  one  of  these  tubes  was  then  fastened  to  the  aspirator, 
and  the  suction  helped  to  evaporate  the  ether  much  in  the  same 
way  that  alcohol  was  used  by  Bunsen,  This  was  repeated  several 
times  without  success.  This  method  was  then  abandoned  and  a 
mixture  of  ground  calcium  cloride  and  snow  was 'used, 
temperature  of  -5°0f  and  froze  a thin  film  of  ice  around  the  test 
tube,  but  the  calcium  chloride  mode  a hard  formation  in  the 
bottom  of  the  tube  that  was  almost  impossible  to  remove,  finally 
a solution  of  three  parts  ice  and  one  part  common  salt  (volume) 
were  used  and  found  to  give  a temperature  of  -15  C.  If  larger 


12. 

quantities  were  used  the  freezing  was  quicker  and  more  satisfact- 
ory. 

See  Photograph  on  page  12a. 


The  specific  heat  of  aluminum  was  then  determined.  The 

test  tube  was  entirely  filled  with  the  mixture  and  allowed  to 

stay  there  until  it  began  to  melt.  This  was  siphoned  out  and 

test  tube  rinsed  with  ice  water  to  prevent  any  formation  of  salt. 

It  was  again  filled  with  the  solution  and  this  time  the  mercury 

fairly  shot  forth  into  2 for  four  or  five  centimeters.  This 

indicated  that  the  ice  was  forming  and  the  next  time  only  two 

centimeters  of  ice  and  salt  were  put  into  the  test  tube.  The 

mercury  gradually  crept  forth  in  the  tube  2 and  this  process  was 

continued  until  the  desired  mantle  of  ice  was  frozen.  A small 

quantity  of  water  at  room  temperature  was  then  weighed  and  put 

into  the  tube.  This  caused  the  mercury  to  recede  in  the  tube  a 

o 

few  centimeters,  and  as  soon  as  it  reached  0 readings  were 
taken.  Next  a small  coil  of  aluminum  wire,  of  known  temperature 
and  mass,  was  lowered  into  the  test  tube  into  which  had  also 
been  poured  enough  water  at  0L  to  cover  the^oil.  The  test  tube 
was  corked  and  the  mercury  tube  observed.  Sometimes  the  aluminum 
caused  the  mercury  to  recede  and  sometimes  it  did  not  but  in 


12a 


A photograph 
for  use,  shewing 
in  snow,  an:i  the 


of  the  apparatus  aft 
the  box  in  which  the 
capille.ry  tube  exten 


er  it  is  set  up 
calorimeter  is 
iin^  along  the 


ready 

packed 

scale. 


*1  7; 

-U^  * 


every  instance,  upon  removing  the  calorimeter  from  the  snow,  it 
was  found  that  a pocket  of  water  had  teen  formed  between  the  test 
tube  and  the  mantle  of  ice.  This  showed  that  the  heat  given  off 


from  the  water  and  the  coil  did  not  melt 

the  ice 

clear  through 

but  only  around  the  test 

tub  9 . 

DATA 

First  Trial 

Second 

Third 

Weight  of  ’Water 

3,1381  gms . 

5.6565 

3.125  gms. 

Weight  of  Aluminum 

3.767 

3.7941 

3.7941 

Divisions  of  recession 
for  Water 

7.3  cm. 

4.2  cm . 

1.8  cm. 

Divisions  of  recession 
for  Aluminum 

1.6  cm. 

1.9  cm. 

1.2  cm . 

Change  of  Temperature 
of  Water 

23.1°  C. 

24.5°  C. 

2£.8°C. 

Change  of  Temperature 
of  Aluminum 

23.5°  C. 

22.6°  C. 

22.8°C; 

Calculated  Specific  Heat 

.182 

.63 

.05 

The  results  of  the  different  trials  are  not  concordant.: 
This  would  appear  to  be  due,  at  least  in  part,  to  the  formation  of 
a water  pocket  about  the  test  tube  as  already  explained.  The  film 
of  ice  about  this  would  tend  to  prevent  a change  in  volume  and  a 
movement  of  the  mercury  column. 

See  photograph  on  page  13a. 

The  modified  calorimeter  was  thought  to  be  so  constructed 
as  to  correct  this  defect.  It  was  made  identical  with  the  first 
one  but  with  small  platinum  ’wires  fused  into  the  end  of  the 
test  tube  (as  shown  in  Figure  5 ) . It  was  thought  that  the  heat 


/ 


\ 


6 


PlAtlNU-n  Wires. 


^ J 

kifrure  5. 

would  "be  conducted  along  these  v.'ires  and  cause  the  ice  to  form  and 
melt  at  the  wires,  thus  allowing  a free  change  in  the  volume. 

Tests  with  the  modified  calorimeter  were  not  taken 
because  a water  leak  appeared  where"  the  wires  were  fused  to  the 
glass . The  instrument  maker  was  unable  to  complete  a second  one 
in  time  for  this  investigation. 

IV  Conclusion.  During  the  course  of  the  investigation, 
a method  was  developed  for  filling  the  calorimeter  so  as  to  ex- 
pel the  air,  a satisfactory  method  of  freezing  was  worked  out 
and  the  pocket  of  water  between  the  ice  and  the  test  tube  was 
found  as  predicted.  Therefore  it  seems  very  likely  that  the 
modified  calorimeter  will  be  an  improvement. 

The  thanks  of  the  author  are  due  to  Professor  B , B. 
Watson  of  the  University  of  Illinois,  who  suggested  the  problem 
and  who  has  given  most  helpful  supervision  during  the  course  of 
the  investigation,  and  to  Miss  Nellie  B.  Bates,  her  partner. 


■ 


BIBLIOGRAPHY 


1.  H,  S.  Gallendar  - "Calorimetry. 

Encyclopoedia  Brittanicia 
Eleventh  Edition  - Volume  5,  -'ages. 

2.  Preston  - "1’heory  of  Heat" 

3.  R . Bunsen  - "The  fee  Calorimeter" 

Philosophical  Magazine  1871,  Volume  XL,  Page  161. 

4.  Canot's  Physics  - Page  448. 

Translated  from  French  by  Mr.  Atkinson. 


